The curvy singer, who in the past has said she’s “proud” not to look like a model, appears quite slim in the video for “Send My Love (To Your New Lover),” which she premiered at the awards show.

Reports speculate that in recent months, the singer has dropped around 30 pounds from her 5-foot-9 frame, thanks to “The Sirtfood Diet,” a book released in the UK in January.

Adele in 2013.Eric McCandless/CBS via Getty Images

Adele’s longtime trainer, Pete Geracimo, is a fan of the meal plan, which focuses on foods that activate sirtuins — proteins in your body that studies have shown help regulate metabolism. Co-authors Glen Matten, a certified nutritionist who specializes in nutritional medicine, and Aidan Goggins, a nutritionist and pharmacist, call out 20 “sirtfoods” that are rich in sirtuin-activating polyphenols, which Matten says “mimic the effects of exercise and fasting.”

The foods are your typical healthy hitters. Dieters nosh on kale, strawberries, dates, olive oil and dark chocolate while drinking green tea, coffee and red wine, among other plant-based treats. Meat is not considered a sirtfood, but dieters are allowed to consume it; the plan focuses on adding sirtfoods to your diet but doesn’t prohibit other foods.

However, it does start out pretty strictly. For the first three days, dieters are limited to just 1,000 calories: one sirtfood-heavy meal recipe from the book (such as salmon with greens, or buckwheat noodles with tofu and vegetables) and three matcha- and kale-packed green juices. For the next four days, the daily allowance is increased to 1,500 calories, with two sirtfood-focused meals and two juices.

After that seven-day entry period, followers eat as many sirtfood-heavy meals as they like. Matten says that after the first week, the diet is more of a gradual shift than a total overhaul, and he hopes readers make small lifestyle changes instead of going all-out and failing. “Our ambition is that in the long term, people are adjusting diets to include these ingredients,” he says.

The results are pretty dramatic, and the weight loss is nearly immediate.

- Glen Matten

But, Matten says, the results are pretty dramatic, and the weight loss is nearly immediate. When he tested the plan on gym-goers, they lost an average of 7 pounds in those first seven days, he says, and looked more toned, thanks to the foods’ supposed muscle-boosting properties.

Although the sirtfood premise is alluring (who wouldn’t want to eat foods that shed pounds and boost muscle?), Grace Fjeldberg, a registered dietitian at the Mayo Clinic, says it’s too early to tell whether the science is accurate.

“The research is promising, and likely uncovers some of the mystery behind why plant-based diets are so beneficial,” Fjeldberg says, but more research is needed. Not everyone will see Adele-like results.

“We’re all very unique, and what our bodies need is going to be very different,” says Fjeldberg.

But, thankfully, most of us don’t have to worry about slimming down for our next music video or red carpet appearance.